Mesh partly shows wireframe upon texturing
You probably have enabled Backface Culling, either in the material's settings if you are in the game engine or in the viewport's shading settings:

Game engine material settings:


Viewport shading settings:


Disable it and you should see the texture of your object on both sides.

This is not a bug in Blender but an optimization technique which is used in games to reduce the GPU load. If you have a closed mesh you can not see the backsides anyway. Only if your mesh is not closed you need to draw both sides.